1. Field of the Invention
This invention relates generally to the field of dishwashers and specifically to a venturi drain system.
2. Description of the Related Art
Dishwashers, particularly those used in domestic applications, have a wash chamber conventionally provided with a sump at a lower part of the wash chamber. Wash liquid sprayed on dishes and other objects in the wash chamber flows downwardly into the sump where the liquid collects. Wash liquid in the sump is recycled to be sprayed on the dishes or directed toward a drain. In some installations, separate pumps (a recycling pump and a drain pump) are used to direct the liquid to the appropriate locations. Examples of these dishwashers are shown in U.S. Pat. Nos. 3,331,374 to Stewart, 5,129,411 to Lagerstrand, 4,998,548 to Lagerstrand, 4,038,103 to Grunewald, 4,168,715 to Spiegel, all incorporated herein by reference. In other installations, a single pump may be used in conjunction with a valve system to direct the liquid to either the drain or the wash chamber. An example of this is shown in U.S. Pat. Nos. 4,243,431 to Dingler and 4,848,382 to Bertsch, incorporated herein by reference.
It is desirable to use a single uni-directional motor to reduce cost and complexity and improve efficiency. Food particles and the material from the dishes should not be recycled and should not interfere with the flow of liquid to the dishes. In addition, it would be desirable to isolate the pump from the food and other material to prevent clogging or damage to the pump.
Jet pumps are known for evacuating fluids from containers. Such jet pumps use a venturi effect to entrain fluid into a flow of a driven fluid. These are described in detail in Gosline, J. E. & O'Brien, M. P., The Water Jet Pump (Univ. of Calif. Publ. Eng. 1934), incorporated herein by reference. It would be desirable to pump food and other material to the drain with the wash liquid using a jet pump.